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Threadripper 3960X 256GB Ram Installed, 128GB/ Half ram showing in Task Manager

Hello Techs!

I just built a Video Editing & VFX system on a TRX40 platform with 256GB RAM (32gb x 8, 3200MHz) – and it looks like windows is only picking up half of it. This is my 2nd build and is very easy to adjust and access. Temps are good, BIOS is up to date, and I just checked all DIMMs & Modules as well as the pins on the processor - Everything is looking sharp on the hardware front (brand new).

• Bios, Task Manager, & CPUz/HWInfo show all 8 sticks at speed, and whether I run the XMP profile for the 3200 speed or set them to default, I get the same result – with my task manager showing 256GB installed but only 128GB Hardware Reserved and available. When Running 4 Dimms it shows 128 with 128 available, and seems fine.

• I checked my boot option in msconfig and it is not limiting my RAM

• I checked BIOS for iGPU settings, but there is no onboard graphics card to mess with and I cannot find a spot to disable anything in BIOS.

• This motherboard supports Quad Channel memory, up to 32GB x 8 @3200, the matched set of G.Skill Ram I have installed is on the supported QVL list from the motherboard manufacturer’s Website (Asrock).

I have searched online & made several BIOS adjustments to no avail, and this limited ram issues has me quite perplexed. I am thinking this might be a simple fix for someone smarter than me, but not sure if it can be diagnosed from the info provided.

I am not sure if I need to disable something in BIOS, but all of my components should play together nicely:

Threadripper 3960X
Noctua Air Cooler (temps: 39c-80c)
Asrock Trx40 Creator (BIOS Verison 1.7)
GSkill 256GB Trident NEO - (8x32GB, 3200)
EVGA RTX 2080 Super (Nvidia Studio Driver)
EVGA 1300W Supernova Gold + PSU

…any help would be appreciated!!


Windows 10 Home is limited to 128 GB. Are you running Home? You’re going to need Pro or Pro Workstation.

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So simple, thank you so much. I will check it out.


If you want to try before you buy you can do a full reinstall as Pro. I think you can run it that way without a license for months before it starts to get really upset at you.

But I think if you upgrade an existing licensed Home to Pro it will want your money right away…I could be wrong about that.

$200 oversight on pro vs home, whoops. I can’t believe i did not even know to check that. I may try for the test “reinstall” and forget my product key. I will post back if it works. So far the machine is performing stable and great for my needs even at the 128, but I just cant let well enough alone.

Out of curiousity, are there similar limitations with linux and other OS options?

It is quite posible to change the windows 10 edition without reinstalling. I have done it myself a number of times.

Stick in a KMS key, and it will upgrade no problem.
W269N-WFGWX-YVC9B-4J6C9-T83GX for win10 pro
Settings —> update & security —> activation —> change product key.

In general, no. It is possible that there is an exception if you are buying Linux from someone Oracle, they might have limits. But something like Debian the limit is theoretical, limited by what the hardware out at the time of release can support.

Wow, is it really that easy?!

I only have a retail license, does that make a difference? Not a large business or volume license.

That key will get you switched for testing, but you need to get a license separately.

You will need to buy a retail win 10 pro key to activate it, and put it on the same location. This does not need to be done right away though.

Alternatively you could buy a retail windows 10 pro key, and input that, and that will both upgrade the edition and activate windows.

It’s not every day they get to download more ram :wink: happy days…

Well yeah, there are Linux build options that do put limits on things. They are generally ridiculously high and you can always rebuild if you need to. Although in some cases you’d have to write the new code yourself.

For Linux, the last I knew, the regular 64 bit kernels are limited to around 2 TiB RAM and 4,096 processor threads. There are also limits on the number of PCIe slots, SATA or SAS ports, USB devices, etc.

Well, I upgraded to windows 10 Pro, and it worked! System is running like a champ now. Thank you !!


You should install linux if you can use it for your use case. Not sure what video editing suit you’re using. Windows has artificial limitations on processor count and memory quantity which i think is bordering on evil.
I ran into this issue on a quad socket machine that I bought used, because windows 10 Pro only supports two sockets. i ended up having to buy a license for windows server and it makes me made every time I think about it. Now there is pro for workstations that (I think) can do more than two sockets.

You know that windows server 2019 preview is free so long as you stay in the beta ring?